Over the past few months, cybercriminals have set up thousands of malicious domains and servers in Brazil in anticipation of the 2016 Olympics in Rio.

Threat data collected by Fortinet from over 2 million sensors worldwide shows that between April and June, the number of malicious URLs detected in Brazil grew by 83 percent. That's an unusually large spike compared to the 16 percent growth in malicious URLs for the rest of the world.

According to a Fortinet report due to be released Tuesday, the number of spoofed domains that are typically used in phishing attacks has also increased, particularly those that try to mimic payment systems and government institutions.

The company's sensors detected over 3,800 malicious websites and URLs containing the government designation ".gov.br" that have likely been set up to target government and other officials involved in the Olympics.

Phishing activity increased 76 percent worldwide between April and June, with Brazil, Colombia, Russia and India representing the top four countries where this type of activity was observed. The top 5 phishing domains with the .br extension were used to spoof popular online banking services.

The Fortinet researchers believe that a large number of cybersecurity attacks will occur during the Rio Olympics, which is not unusual for such an event. However, compared to previous Olympic games, more of the attacks are likely to succeed because cyber threats are not treated as a very high priority in Brazil, they said.

According to a World Economic Forum (WEF) survey, businesses in Brazil ranked data fraud and theft as 16th among the risks they're concerned about, while cyberattacks were ranked 23rd. By comparison, U.S. businesses view cyberattacks as the number one risk and for those in the U.K. it's the number two concern.

"This level of aggregation and protection does not happen without the right priority and investments for cyber attacks," and is unlikely to apply in Brazil, the Fortinet researchers said in their report.